Impact of pulsed electric field pre-treatment on nutritional and polyphenolic contents and bioactivities of light and dark brewer's spent grains

Abstract Pulsed electric field (PEF) pre-treatment, at 2.8 kV/cm with 3000 pulses of 20 μs pulse-width, was applied on brewer's spent grains (BSG) followed by aqueous extraction at 55 °C, 220 rpm for 16 h. PEF pre-treatment showed significantly increased yields ( p p d -glucose and total free amino acids (18.5–33.3 and 21–25 mg/g dry weight extract (Dwe)), compared to dark extracts (5 and 1.2 mg/g Dwe respectively). Dark BSG extracts showed significantly higher ( p Salmonella typhimurium and Listeria monocytogenes , respectively compared to the untreated extracts (>50 mg/mL) with lowest MIC value of 1.56 mg/mL against Staphylococcus aureus . All the BSG extracts induced the release of pro-inflammatory cytokines (IL-1β, IL-6, TNF-α) and chemokines (IL-8, MCP-1 and MIP-1α) confirming immunomodulatory activity.